254 EATE OF GROWTH OF SOME SEA FISHES. 



years 1873, 1874, 1875, 1876, and a trace of it in 1878, ttat is in 

 five years only out of twenty-five of which he gives the " regime." 

 In the years in which it occurred the fish caught in June were 

 15 to 17 cm. long. But in many years, in which the diminution in 

 July is not observable, the fish caught in June are no larger than 

 the poisson de Juillet ; for instance, in 1877, 1878, 1879, 1883, 1884. 

 Such facts as these, it seems to me, are not surprising when we 

 consider that the pilchard has a spawning period of five or six 

 months, and that its movements are probably not regular. Pro- 

 bably fish 15 or 16 cm. long, caught in June, are fish hatched 

 unusually early in the preceding season, while those of 13 to 14 cm. 

 are produced from a later spawning. In some years the fish are 

 throughout the season of unusually small size, and this may be due 

 to a scarcity of food in the preceding winter. The very small fish 

 occurring in 1887 in September and October were ll'O to ITS cm. 

 long, and probably were derived from eggs shed the preceding May 

 and June, having grown unusually fast. 



I quite agree with Pouchet that it is impossible to obtain from 

 the industrial records satisfactory evidence of the actual increase in 

 size of the sardine from the beginning to the end of the fishing 

 season. The data we have to deal with, even when the calculations 

 are arithmetically correct, as Pouchet's ai'e not, are such distant 

 approximations, and it is so evident that in most cases we are not 

 comparing the average sizes of the same shoals, that no great im- 

 portance can be attached to the difference in size shown between 

 the fish in different months. All that can be said is that usually a 

 difference of 2'5 to 3-5 cm. in length is the result of comparing the 

 sizes of the fish given for July and October. 



The subject of the nets used in the French fishery deserves some 

 mention. Unfortunately Professor Pouchet does not give a complete 

 account of them ; but he states in one place that the mesh is 

 measured by the length occupied by five knots, that is a length 

 equal to four times the side of one mesh, and I find from the figures 

 he gives that the mesh of the nets used varies from ^ths to i^ths 

 of an inch. I gather that the nets here referred to are drift nets 

 used with the bait or rogue, for it is stated that the fishermen 

 change their nets to suit the varying size of the fish, which they 

 would not need to do if they were using a suitable seine. Thus, 

 some of the nets used in the French fishery have the same mesh as 

 those we have been using at Plymouth. It must be remembered 

 that Professor Pouchet only refers to the fish caught by the 

 fishermen ; he denies that there ai^e ever any still smaller fish a few 

 weeks or months old in the waters where the fishery is carried on, 

 but as the nets used could not catch these smaller fish of 3 to 7 or 



